Catalytic reaction of aromatics and olefins in the presence of acidic zeolite catalysts has been used in most of the advanced chemical processes for the production of alkyl aromatic compounds such as cumene and ethylbenzene. Since the early 1990s, new zeolite-based cumene technologies have been developed by Mobil/Badger, Dow/Kellogg, UOP, and others. These cumene technologies carry out the alkylation of benzene and propylene in liquid phase in the presence of a solid acidic zeolite catalyst. A process developed by CDTech effects alkylation of benzene and propylene in mixed phases in a catalytic distillation column which houses both distillation devices and bales of zeolite catalysts. Catalysts that can be used for alkylation of benzene with propylene and also for transalkylation of benzene and polyisopropylbenzenes in liquid phase include zeolite beta, zeolite Y, zeolite omega, ZSM-5, ZSM-12, MCM-22, MCM-36, MCM-49, MCM-56, MCM-58, MCM-68, Faujasite, Mordenite, porous crystalline magnesium silicates, and tungstate modified zirconia, all of which are known in the art.
MCM-22 and its use to catalyze the synthesis of alkyl aromatics are described, for example, in U.S. Pat. No. 4,954,325 (Rubin), U.S. Pat. No. 4,992,606 (Kushnerick), U.S. Pat. No. 5,077,445 (Le), U.S. Pat. No. 5,334,795 (Chu), and U.S. Pat. No. 5,900,520 (Mazzone), each of which is incorporated herein by reference. MCM-36 and its use in the synthesis of alkyl aromatics are described in U.S. Pat. No. 5,250,277 (Kresge), U.S. Pat. No. 5,292,698 (Chu), and U.S. Pat. No. 5,258,565 (Kresge), each of which is incorporated herein by reference. MCM-49 and its use in the synthesis of alkyl aromatics are described in U.S. Pat. No. 5,236,575 (Bennett), U.S. Pat. No. 5,493,065 (Cheng) and U.S. Pat. No. 5,371,310 (Bennett), each of which is incorporated herein by reference. MCM-56 and its use to catalyze the synthesis of alkyl aromatics are described in U.S. Pat. No. 5,362,697 (Fung), U.S. Pat. No. 5,453,554 (Cheng), U.S. Pat. No. 5,536,894 (Degnan), U.S. Pat. No. 5,557,024 (Cheng), and U.S. Pat. No. 6,051,521 (Cheng), each of which is incorporated herein by reference. MCM-58 and its use for the production of alkyl aromatics are described in U.S. Pat. No. 5,437,855 (Valyocsik) and U.S. Pat. No. 5,569,805 (Beck), each of which is incorporated herein by reference. MCM-68 and its use for the production of alkyl aromatics are described in U.S. Pat. No. 6,049,018 (Calabro), which is incorporated herein by reference.
The use of tungstate modified zirconia to catalyze the synthesis of alkyl aromatics is described in U.S. Pat. No. 5,563,311 (Chang), which is incorporated herein by reference. U.S. Pat. No. 5,081,323 (Innes), which is incorporated herein by reference, teaches a liquid phase alkylation or transalkylation process using zeolite beta. Production of cumene over zeolite Y is described in U.S. Pat. No. 5,160,497 (Juguin) and U.S. Pat. No. 5,240,889 (West), which are incorporated herein by reference. U.S. Pat. No. 5,030,786 (Shamshoum) and U.S. Pat. No. 5,980,859 (Gajda), and European patent 0,467,007 (Butler), which are incorporated herein by reference, describe the production of alkyl aromatic compounds with zeolite Beta, zeolite Y, and zeolite Omega. U.S. Pat. No. 5,522,984 (Gajda), U.S. Pat. No. 5,672,799 (Perego), U.S. Pat. No. 5,980,859 (Gajda), and U.S. Pat. No. 6,162,416 (Gajda), which are incorporated herein by reference, teach the production of cumene with zeolite beta. Use of zeolite Mordenite in production of monoalkylated benzene such as cumene and ethylbenzene is described in U.S. Pat. No. 5,198,595 (Lee), which is incorporated herein by reference. Production of ethylbenzene with ex situ selectivated zeolite catalyst is described in U.S. Pat. No. 5,689,025 (Abichandani), which is incorporated herein by reference.
The first zeolite-based ethylbenzene process, developed jointly by Mobil and Badger in the early 1980s, utilized vapor phase alkylation of benzene with ethylene and vapor phase transalkylation of benzene and polyethylbenzene. Both the alkylation and transalkylation steps of this early process were carried out in the presence of solid acidic ZSM-5 catalysts. Production of ethylbenzene with ZSM-5 is described in U.S. Pat. No. 5,157,185 (Chu), which is incorporated herein by reference.
Several liquid phase zeolite-based ethylbenzene technologies were developed in the late 1980s and in the 1990s by UOP/Lummus, Mobil/Badger, and others. Alkylation of benzene with ethylene and transalkylation of benzene and polyethylbenzenes were carried out in liquid phase in the presence of solid acidic zeolite catalysts. Catalysts that can be used for alkylation of benzene with ethylene and transalkylation of benzene and polyethylbenzenes in liquid phase processes include zeolite beta, zeolite Y, zeolite omega, ZSM-5, ZSM-12, MCM-22, MCM-36, MCM-49, MCM-56, MCM-58, MCM-68, Faujasite, Mordenite, porous crystalline magnesium silicates, and tungstate modified zirconia. A process developed by CDTech effects alkylation of benzene and ethylene in mixed phases in a catalytic distillation column which houses both distillation devices and bales of zeolite catalysts.
Production of ethylbenzene over intermediate pore size zeolites is described in U.S. Pat. No. 3,751,504 (Keown), U.S. Pat. No. 4,547,605 (Kresge), and U.S. Pat. No. 4,016,218 (Haag), which are incorporated herein by reference. U.S. Pat. No. 4,169,111 (Wight) and U.S. Pat. No. 4,459,426 (Inwood), which are incorporated herein by reference, disclose production of ethylbenzene over large pore size zeolites such as zeolite Y. Synthesis of zeolite ZSM-12 is described in U.S. Pat. No. 5,021,141 (Rubin), which is incorporated herein by reference. A process for ethylbenzene production over zeolite ZSM-12 is described in U.S. Pat. No. 5,907,073 (Kumar), which is incorporated herein by reference. Production of ethylbenzene over zeolite Mordenite is described in U.S. Pat. No. 5,430,211 (Pogue), which is incorporated herein by reference. Liquid phase synthesis of ethylbenzene with zeolite Beta is described in U.S. Pat. No. 4,891,458 (Innes) and U.S. Pat. No. 6,060,632 (Takamatsu), which are incorporated herein by reference. U.S. Pat. No. 4,849,569 (Smith), U.S. Pat. No. 4,950,834 (Arganbright), U.S. Pat. No. 5,086,193 (Sy), U.S. Pat. No. 5,113,031 (Sy), and U.S. Pat. No. 5,215,725 (Sy), which are incorporated herein by reference, teach various systems for the catalytic distillation production of alkylated aromatic compounds, including ethylbenzene and cumene.
U.S. Pat. No. 5,902,917 (Collins), which is incorporated herein by reference, teaches a process for producing alkylaromatics, especially ethylbenzene and cumene, wherein a feedstock is first fed to a transalkylation zone and the entire effluent from the transalkylation zone is then cascaded directly into an alkylation zone along with an olefin alkylating agent, especially ethylene or propylene.
U.S. Pat. No. 6,096,935 (Schulz), which is incorporated herein by reference, teaches a process for producing alkyl aromatics using a transalkylation reaction zone and an alkylation reaction zone. The transalkylation reaction zone effluent passes to the alkylation reaction zone where aromatics in the transalkylation reaction zone effluent are alkylated to the desired alkyl aromatics. U.S. Pat. Nos. 6,232,515 and 6,281,399 (Schulz), which are incorporated herein by reference, teach further details of processes for producing ethyl and isopropyl aromatics using a transalkylation reaction zone and an alkylation reaction zone.
U.S. Pat. No. 6,479,721 (Gadja), which is incorporated herein by reference, teaches a process for the alkylation of aromatics with olefins using a solid catalyst wherein the olefin ratio and/or the maximum olefin concentration in the alkylation catalyst bed is maintained less than an upper limit to reduce the catalyst deactivation rate and the formation of diphenylalkanes.
PCT published application WO02062734 (Chen), which is incorporated herein by reference, teaches a process for producing a monoalkylation aromatic product, such as ethylbenzene and cumene, utilizing an alkylation zone and a transalkylation zone in series or a combined alkylation and transalkylation reactor zone. This invention claims to minimize the amount of excess aromatic material that is used and needs to be recovered and subsequently circulated, thus minimizing the production cost.
U.S. Pat. No. 6,313,362 (Green), which is incorporated herein by reference, teaches an aromatic alkylation process in which the alkylation product is contacted with a purification medium in a liquid phase pre-reaction step to remove impurities and to form a purified stream. The purified stream may then be further processed by liquid phase transalkylation to convert the polyalkylated aromatic compound to a monoalkylated aromatic compound. The process may use a large pore molecular sieve catalyst such as MCM-22 as the purification medium in the pre-reaction step because of its high reactivity for alkylation, strong retention of catalyst poisons, and low reactivity for oligomerization under the pre-reactor conditions. Olefins, diolefins, styrene, oxygenated organic compounds, sulfur-containing compounds, nitrogen-containing compounds and oligomeric compounds are claimed to be removed by this process.
U.S. Pat. No. 4,358,362 (Smith), which is incorporated herein by reference, teaches a method for enhancing catalytic activity of a zeolite catalyst by contacting a feed stream which contains a catalytically deleterious impurity with a zeolitic sorbent. This invention is applicable to a variety of processes including dewaxing, with an example illustrating a temperature reduction of 100° F. of the initial equilibrium (lineout) temperature by the method of the invention.
Japanese patents JP4198139 and 717536 (Hidekichi), which are incorporated herein by reference, teach a production process for alkylbenzene including a step of pretreatment of benzene for reduction of base compounds prior to the alkylation of benzene over acid catalysts. The removal of basic material in benzene is achieved by contacting the benzene feed stream with clay, zeolite, activated coal, silica gel, alumina, and ion exchange resin.
U.S. Pat. No. 4,973,790 (Beech), which is incorporated herein by reference, teaches a process for oligomerizing C2 to C10 olefins obtained by catalytic cracking of heavy crude oil. The olefins are oligomerized in the presence of added hydrogen over a shape-selective zeolite to gasoline and distillate products. Feed pretreatment to remove basic nitrogen compounds present in the light olefin refinery stream uses a water wash or a guard bed to improve catalyst life.
A process for upgrading of unstable olefins, naphthas, and dienes, such as coker naphthas, is taught in U.S. Pat. No. 5,053,579 (Beech), which is incorporated herein by reference. The olefins are oligomerized over a zeolite catalyst to gasoline and distillate products. Addition of hydrogen and feed pretreatment to remove basic nitrogen compounds are taught to improve catalyst life. Water washing of coker naphtha is the preferred method of removing basic nitrogen compounds.
A process of producing linear alkyl benzene (LAB) is taught in U.S. Pat. No. 5,245,094 (Kocal), which is incorporated herein by reference. The catalyst life and the product linearity are improved by treating the olefinic feedstock obtained from dehydrogenation of paraffins to reduce the aromatics content thereof.
The positive or negative effects of moisture in zeolite catalyst and in the feed are discussed in several publications. For example, U.S. Pat. No. 5,030,094 (Shamshoum), which is incorporated herein by reference, teaches a process for production of ethylbenzene in which the catalyst lifetime is increased by reducing the concentration of water in the feed to the reactor. By contrast, U.S. Pat. No. 5,240,889 (West), which is incorporated herein by reference, teaches a catalyst composition for catalyzing the alkylation and transalkylation reactions in the production of ethylbenzene and cumene. This patent, however, teaches that increasing the water content in the catalyst increases the catalyst life.
U.S. Pat. No. 5,300,722 (Amundsen), which is incorporated herein by reference, teaches an oxygen-free aromatic alkylation process. In this process, an aromatic hydrocarbon is contacted with an alkylating agent in a reactor vessel in the absence of oxygen and in the presence of a silica-containing molecular sieve catalyst under liquid phase alkylation conditions. The absence of oxygen is said to significantly improve the catalyst life.
U.S. Pat. No. 5,744,686 (Gajda), which is incorporated herein by reference, teaches a process for the removal of nitrogen compounds from an aromatic hydrocarbon stream by contacting the stream with a selective adsorbent having an average pore size less than about 5.5 Angstroms. The selective adsorbent is a non-acidic molecular sieve selected from the group consisting of pore closed zeolite 4A, zeolite 4A, zeolite 5A, silicalite, F-silicalite, ZSM-5, and mixture thereof. One embodiment taught in this patent includes a combination of a fractionation zone and an adsorption zone.
U.S. Pat. No. 5,942,650 (Gajda), which is incorporated herein by reference, is an extension of U.S. Pat. No. 5,744,686 and applies the invention to aromatic alkylation with ethylene and propylene, isomerization, and disproportionation. The pore size of the catalyst used for those reactions is at least 6 Angstroms.
A process for preparing an alkylated benzene or mixture of alkylated benzenes is taught in U.S. Pat. No. 6,297,417 (Samson), which is incorporated herein by reference. The process includes contacting a benzene feedstock with a solid acid, such as acidic clay or acidic zeolite, in a pretreatment zone at a temperature between about 130° C. and about 300° C. It is taught that such a pretreatment step improves the lifetime of the alkylation and transalkylation catalyst.
U.S. Pat. No. 6,355,851 (Wu), which is incorporated herein by reference, teaches a zeolite-catalyzed cumene synthesis process in which benzene and propylene feedstocks are pretreated to remove catalyst poisons. The benzene feedstock is pretreated under pressure by contact with a “hot” clay bed at a temperature of about 200 to 500° C., followed by distillation of the benzene feedstock to separate the benzene from the higher molecular weight materials formed from olefinic poisons during the hot clay treatment The benzene feed is also subjected to a “cold” clay treatment wherein the benzene distillate is contacted with an ambient-temperature clay. The propylene feedstock is pretreated by contact with an alumina to remove trace sodium compounds and moisture, a molecular sieve to remove water, and two modified aluminas to remove catalyst poisons. The pretreated propylene and benzene feedstocks are then reacted in the presence of a zeolite catalyst to form cumene without causing rapid degradation of the catalyst's activity.
A method for purifying olefin-containing feed streams in polymerization or alkylation processes, which is characterized by the fact that the feed stream is passed over an adsorption layer is taught in PCT published application WO0107383, which is incorporated herein by reference.
PCT published application WO0214240 (Venkat), which is incorporated herein by reference, teaches removal of polar contaminants in an aromatic feedstock by contacting it with molecular sieves with pore size greater than 5.6 Angstroms at temperatures below 130° C.
These prior art processes, however, fail to teach a complete and consistently effective approach to eliminating deleterious substances from hydrocarbon feedstocks used for alkylation and/or transalkylation processes to prevent poisoning of the acidic zeolite catalysts preferred for such processes. The limitations and deficiencies of these prior art techniques are overcome in whole or at least in part by the improved integrated processes of this invention.